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| author | Larry Finger <Larry.Finger@lwfinger.net> | 2022-11-03 20:27:50 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-08 16:26:42 +0100 |
| commit | bb5b5e2104ca000888df89e35ff42c677df22671 (patch) | |
| tree | 0d51867e08f8be49486258b84763ae3926221de9 | |
| parent | staging: r8188eu: change return type of rtw_set_802_11_disassociate to void (diff) | |
| download | linux-bb5b5e2104ca000888df89e35ff42c677df22671.tar.gz linux-bb5b5e2104ca000888df89e35ff42c677df22671.zip | |
staging: rtl8192e: Fix divide fault when calculating beacon age
When the configuration parameter CONFIG_HZ is less that 100, the compiler
generates an error as follows:
../drivers/staging/rtl8192e/rtllib_wx.c: In function 'rtl819x_translate_scan':
../drivers/staging/rtl8192e/rtllib_wx.c:220:57: warning: division by zero [-Wdiv-by-zero]
220 | (jiffies - network->last_scanned) / (HZ / 100));
| ^
In file included from ../include/linux/skbuff.h:45,
from ../include/linux/if_ether.h:19,
from ../include/linux/etherdevice.h:20,
from ../drivers/staging/rtl8192e/rtllib_wx.c:18:
../drivers/staging/rtl8192e/rtllib_wx.c: In function 'rtllib_wx_get_scan':
../drivers/staging/rtl8192e/rtllib_wx.c:261:70: warning: division by zero [-Wdiv-by-zero]
261 | (jiffies - network->last_scanned) /
|
In fact, is HZ is not a multiple of 100, the calculation will be wrong,
but it will compile correctly.
The fix is to get rid of the (HZ / 100) portion. To decrease any round-off
errors, the compiler is forced to perform the 100 * jiffies-difference
before dividing by HZ. This patch is only compile tested.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/20221104012750.2076-1-Larry.Finger@lwfinger.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/rtl8192e/rtllib_wx.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/staging/rtl8192e/rtllib_wx.c b/drivers/staging/rtl8192e/rtllib_wx.c index da2c41c9b92f..217426ee2e92 100644 --- a/drivers/staging/rtl8192e/rtllib_wx.c +++ b/drivers/staging/rtl8192e/rtllib_wx.c @@ -217,7 +217,7 @@ static inline char *rtl819x_translate_scan(struct rtllib_device *ieee, p = custom; p += scnprintf(p, MAX_CUSTOM_LEN - (p - custom), " Last beacon: %lums ago", - (jiffies - network->last_scanned) / (HZ / 100)); + (100 * (jiffies - network->last_scanned)) / HZ); iwe.u.data.length = p - custom; if (iwe.u.data.length) start = iwe_stream_add_point_rsl(info, start, stop, @@ -258,8 +258,8 @@ int rtllib_wx_get_scan(struct rtllib_device *ieee, escape_essid(network->ssid, network->ssid_len), network->bssid, - (jiffies - network->last_scanned) / - (HZ / 100)); + (100 * (jiffies - network->last_scanned)) / + HZ); } spin_unlock_irqrestore(&ieee->lock, flags); |